This invention relates to substituted 2,4-diarylpyrimidines and to their use in herbicidal formulations. In particular, this invention relates to substituted 2,4-diarylpyrimidines of the formula ##STR3## wherein R is selected from the group consisting of ##STR4## R.sub.1 and R.sub.2 are independently selected from the group consisting of H, Br, Cl, F, C.tbd.N, CF.sub.3 and OCF.sub.3 ;
R.sub.3 is selected from the group consisting of H, C.sub.1 -C.sub.4 alkyl, CO.sub.2 CH.sub.3, CO.sub.2 CH.sub.2 CH.sub.3, CH.sub.2 Cl, CH.sub.2 OCH.sub.3, CH.dbd.CH.sub.2, C.sub.1 -C.sub.3 thioalkyl, and C.sub.1 -C.sub.3 alkoxy;
R.sub.4 is selected from the group consisting of H, --OH, C.sub.1 -DC.sub.4 alkyl, C.sub.1 -C.sub.3 thioalkyl, C.sub.1 -C.sub.3 alkoxy; and PA0 R.sub.5 is selected from the group consisting of H and F.
The compounds of the present invention, as will be seen from the description and test data which follows, have utility as both pre-emergence and post-emergence herbicides, against a wide range of plant species. The preferred method of application is pre-emergence, and is particularly useful on wheat, corn, soy, milo and rice crops in view of its selectivity.
The terms "herbicide" and "herbicidal" are used herein to denote the inhibitive control or modification of undesired plant growth. Inhibitive control and modification include all deviations from natural development such as, for example, total killing, growth retardation, defoliation, desiccation, regulation, stunting, tillering, stimulation, leaf burn, and dwarfing. The term "herbicidally effective amount" is used to denote any amount which achieves such control or modification when applied to the undesired plants themselves or to the area in which these plants are growing. The term "plants" is intended to include germinant seeds, emerging seedlings and established vegetation, including both roots and above-ground portions.